Digital Wellbeing Settings & Widget

### Feature Description

It would be nice to have a Digital Wellbeing page (or maybe even a widget) in the Settings app to help users keep track of how much time they spend on their computer.

Some ideas for what it could include:

- Daily and weekly screen time.
- Time spent in each application.
- A focus mode that hides notifications or blocks selected apps.
- Break reminders (like the 20-20-20 rule or stretch reminders).
- Optional screen time goals or limits.

### Use Case

I spend a lot of time on my computer, and it's easy to lose track of time while working, studying, or gaming.

Having something built into DMS would make it easier to see where my time goes, remind me to take breaks, and stay focused when I need to. It would also be nice to have this built in instead of using a separate application.

### Compositor(s)

All compositors

### If Other, please specify

_No response_

### Proposed Solution

_No response_

### Alternatives/Existing Solutions

Android Digital Wellbeing
Apple's Screen Time (iOS/macOS)
GNOME's Wellbeing settings (screen time and break reminders)

No files, tests, or implementation entry points are named. Start by reviewing the Settings app and how DankMaterialShell supports all compositors, then narrow the feature to a defined first milestone with measurable screen-time data, supported compositors, and completion criteria.

Written by the indexing model from the issue text.